PROCESS FOR PRODUCING POLYPHENYLENE ETHER

PROBLEM TO BE SOLVED: To provide a process for producing a polyphenylene ether wherein the polymerization of a polyphenylene ether is stopped and a metal catalyst is recovered. SOLUTION: In the process for producing a polyphenylene ether by polymerizing a polyphenylene ether in a nonaqueous polymerization solvent in the presence of a catalyst to give a polyphenylene ether solution, bringing the obtained solution into contact with an aqueous solution of a chelating agent to form a chelate compound of a metal catalyst to stop the polymerization, separating the aqueous solution containing the chelate compound of the metal catalyst from the polyphenylene ether solution, and adding an alkali metal sulfide to the aqueous solution to deposit the metal catalyst as its sulfide in the form of a solid material from the aqueous solution, the sulfide of the metal catalyst is subjected to solid-liquid separation by a rotary continuous vacuum filtration system in which a filter aid layer is formed on the surface of a filter medium.